I've done CPC advertising with Facebook and found the quality of traffic to be lower than G/Y/M but the lower CPC cancels out and makes my cost per conversion similar.

I tried Facebook for a while. My CTR was lower than Google. I suspect this is because you're targeting impressions in a totally different manner. That being said, clicks are usually cheaper and conversions off my landing page were decent.

Another thing that bugged me about Facebook was that my Google Analytics numbers for visitors from FB never matched what FB was charging me. FB always showed roughly 1-5% more clicks than GA showed visitors.

It DEFINITELY depends on your site. I've been far more successful with facebook ads because my site targets males 18-35 who smoke and have certain words in their profiles.

It kicks the shit out of adwords, but I imagine this is due to my content.

I have done several campaigns on Facebook and found the CTR to be higher than Adwords, and CPC was lower. Unfortunately I found that traffic from Facebook didn't stick very well, so it was a wash.